Amount Of Substance Flashcards
What is Relative Molecular Mass?
mass of a molecule in comparison to 1/12 the relative atomic mass of an atom of carbon 12
What is Relative Atomic Mass?
The average mass of an element compared to 1/12th the relative atomic mass of an atom of carbon 12
What is Relative Formula Mass used for?
Ionic compounds because they don’t exist as molecules
What is Avogadros constant?
6.022 x 10^23 which is the number of atoms in 12g of carbon 12
What is a mole?
The amount of substance containing 6.022 x 10^23
What is the equation involving moles, volume and concentration (+units)
Moles = concentration (mol dm^-3) x volume (dm^3)
What is the equation linking moles, mass and Mr (+units)
Moles = mass / Mr
mass- grams
What is the ideal gas equation (+units)
PV = nRT Pressure- Pa Volume- m^3 Gas constant (8.31)- J K-1 mol-1) Temperature- K
How is volume calculated from the ideal gas equation?
V= nRT / P
How is pressure calculated from the ideal gas equation?
P = nRT / V
How is the number moles calculated from the ideal gas equation?
n = PV / RT
What is Empirical Formula?
The simplest whole number ratio of the atoms of each element present in a compound
How is Empirical formula calculated?
- Find the mass of each element
- Work out the no. of moles of each element (mass / mr)
- Convert number of moles into a whole number ratio
What is the molecular formula?
Actual number of atoms of each element in one mole of a compound (only substances that exist as molecules)
How is molecular formula calculated?
Relative molecular mass/relative mass of empirical formula
